混合场中(Pr_(1-y)Nd_y)_(2/3)Sr_(1/3)MnO_3体系磁转变行为研究

Study on magnetic transition behavior for (Pr_(1-y)Nd_y)_(2/3)Sr_( 1/3)MnO_3 system under superposed fields

对 (Pr1 -yNdy) 2 3Sr1 3MnO3(y=2 8,4 8,6 8)体系在 4 2K— 30 0K温度范围内混合场 (即交流驱动场Hac与附加直流磁场Hdc的叠加 )下的磁转变行为进行了系统的实验研究 .结果表明 ,随着外加直流磁场强度的增大 ,样品的直流磁化强度增大 ,交流磁化率逐渐减小 ;在混合场作用下 ,磁转变温度 (居里温度 )附近样品交流磁化率的实部出现一个特征的尖峰 .对于 (Pr1 -yNdy) 2 3Sr1 3MnO3体系 ,随着Nd掺杂量的增加 ,交流磁化率实部的相对变化 (Eχ′ =Δχ′ χ′dc)的峰值对应的温度降低 ,这一点与该系统的磁电阻的变化规律一致 .对锰氧化物体系在混合场中的磁转变现象进行了讨论 .

The magnetic transition behaviors of (Pr1-yNdy)(2/3)Sr1/3MnO3 (y = 2/8,4/8,6/8) polycrystalline samples under superposed magnetic fields (i.e., the superposed ac and dc magnetic field) were systematically studied at temperatures ranging from 4.2 to 300K. The results showed that the magnetization increases with the increase of magnetic field, and the real part of the ac susceptibility decreases as the superposed dc magnetic field increases. Under the superposed magnetic field, a characteristic sharp peak of the real part of the susceptibility appears near the magnetic transition temperature (Curie temperature). For the (Pr1-yNdy)(2/3)Sr/3MnO3 system, as the Nd content increases, the peak temperature of the relative variation of the real part of susceptibility (E-chi' = Deltachi'/chi'(dc)) decreases, in consistent with that of the magnetoresistivity of this system. The magnetic transition behaviors under superposed magnetic fields for the manganite systems are discussed.